Southern California's biggest transit agency retired its last diesel bus six years ago, capping a 15-year process to replace tailpipes that belched black smoke with quieter, cleaner engines powered by natural gas.
Now, Los Angeles County transportation leaders are working toward a bolder goal: buses that don't pollute at all.
The Metropolitan Transportation Authority has begun to plan how to eliminate emissions from its fleet by 2030, a move that will require buying more than 2,300 buses that run on electric batteries or another form of zero-emission power, such as hydrogen.
Metro's ambitious goal, at a time when no other major U.S. transit agency owns more than a handful of battery-powered buses, would make Los Angeles a proving ground for a relatively untested technology.
But the 2030 benchmark has prompted some questions from critics about how much Metro should spend on electric buses while the technology is still new and expensive. Supporters have said the agency's investment could help a budding industry that pledges significant air-quality benefits.
"We have two choices," said Metro chairman and Los Angeles Mayor Eric Garcetti, who introduced the 2030 goal. "We can wait for others, and follow, at the expense of residents' health — or lead and innovate, and reduce emissions as quickly as possible. I'd much rather do the latter."
Next week, Metro's directors are expected to approve the first steps toward electrifying the bus fleet. The board will consider a $138-million proposal to buy 95 electric buses for two lines and to install the charging infrastructure needed to keep them running.
Metro's first electric buses will operate only along the Orange Line busway in the San Fernando Valley and in the 29-mile Silver Line along the Harbor and San Bernardino freeways, officials said. Both routes will be equipped with charging stations where buses can "top off" if they run low on power.
Converting the Orange and Silver lines to electric power will be a leap of faith for some Metro employees, who wrote in a recent report that zero-emission buses today pose "significant risks to service and operation."
Though their batteries have grown lighter and more efficient, electric buses still can't travel as far as their natural gas-powered counterparts, which often run more than 400 miles on a single tank.
"We have a high degree of confidence that with today's technology, on those two lines, we'll have great service," said John Drayton, Metro's director of vehicle technology. "But going forward, we want to see this technology improve a bit more."
Historically, transit officials have been skeptical of technology that could interfere with providing reliable, safe service, said Joshua Shaw, the executive director of the California Transit Assn., a Sacramento-based trade group.
"Our industry is conservative in the sense that every morning, we have to have the buses out of the gate on time to serve people," Shaw said. Officials with reservations, he said, see that electric buses "have emission benefits, but might break down more frequently, or have a net gain on operating costs."
Each year, Metro replaces about 7% of its bus fleet, which is the nation's second largest after New York's. To meet Garcetti's goal of a zero-emission fleet by 2030, the agency will need to start buying about 200 electric buses annually starting in 2019, officials said.
By then, Drayton said, Metro will need to see an array of electric buses with a top speed of 65 mph and a range of at least 250 miles. Those features are required to handle the demands of Metro's workhorse local and rapid routes, which often require vehicles to stay in mixed traffic for 20 hours without refueling.
"One of my nightmare scenarios is if we had to put chargers all across L.A. County," Drayton said. "How would you even approach that?"
In the next two years, Metro will plan how to upgrade the wiring to accommodate higher wattages at stations and bus yards where the vehicles would recharge, and evaluate how those costly improvements would be funded.
Currently, each electric bus costs at least $200,000 more than its natural-gas counterpart. That figure does not include infrastructure upgrades and charging stations, costs that Garcetti said could be paid by the companies providing the buses.
Garcetti said electric buses will become cheaper than their gas counterparts some time in the next decade, and that Metro's transition to zero-emission buses could happen "much more quickly" than 2030.
Still, Metro Chief Executive Phil Washington said, the hope is that Metro can transition to electric power without retiring natural-gas buses that could still run for several more years. Typically, the agency's buses stay on the road for about 14 years.
In the long term, Garcetti said, the higher start-up costs will be worth it. In addition to the air pollution benefits, he said, the streets will be quieter.
Metro has proposed a budget of $72 million for replacing the Orange Line's buses. That includes $51 million for 35 electric buses from New Flyer of America Inc., and $7.8 million for charging stations at both ends of the line. The route should be fully electric by 2020, officials said.
Similar changes to the Silver Line will cost almost $66 million, officials said. That figure includes buying 60 electric buses from BYD, installing chargers along the route, and updating wiring to handle higher wattages. The line should be finished by 2021, officials said.
Metro's first major electric bus purchase would represent less than 5% of the agency's fleet, but would at least double the number of electric buses in use in California — a "momentous market adjustment," Shaw said.
"Everybody will be looking to L.A. as the chance to learn, for better or worse, what the implications are," Shaw said.
Advocates have urged Metro to invest in electric technology not only to reduce transit emissions, which are responsible for a fraction of the transportation sector's harmful pollutants, but to encourage the trucking and freight industry to make the same change.
"You need to treat your role as a proving ground for durability, reliability, cost and other factors for the heavy-duty industry generally — not just for your fleet," said Denny Zane, the executive director of the nonprofit organization Move L.A., at a recent Metro meeting. "This is a much bigger issue to ponder."
Gas stakeholders have urged Metro to adopt a new engine technology they call "near zero," which runs on renewable natural gas. Installing those engines would provide more immediate air quality benefits, they said.
"We do have concerns about the board entertaining policy that's based on mandating a technology in a set number of years before they've really tested that technology," said George Minter, a regional vice president at the Southern California Gas Co.
Garcetti said he would not include the "near zero" buses in his 2030 policy, but said they could be a stopgap solution for the next 13 years.
Gas advocates have also said Metro will charge bus batteries using electricity from the Los Angeles Department of Water and Power, which still draws some energy from coal-fired power plants. The city has said it hopes to eliminate coal from its power mix by 2025.
What both sides agree on is that the concerns over new engine technology are nothing new. When Metro first purchased compressed natural gas buses in the 1990s, they cost $50,000 more than diesel vehicles, and the agency paid steep fees to install gas compressors in bus yards.
Early on in the push for natural gas, the gas tank in one of Metro's first natural-gas buses exploded during a refueling. No one was injured, but Metro pulled all the buses from the road for a month.